Centre for Evolutionary Biology, School of Animal Biology (M092), The University of Western Australia, Crawley, WA, Australia.
J Evol Biol. 2012 Apr;25(4):748-58. doi: 10.1111/j.1420-9101.2012.02469.x. Epub 2012 Feb 22.
Polyphenic traits are widespread and represent a conditional strategy sensitive to environmental cues. The environmentally cued threshold (ET) model considers the switchpoint between alternative phenotypes as a polygenic quantitative trait with normally distributed variation. However, the genetic variation for switchpoints has rarely been explored empirically. Here, we used inbred lines to investigate the genetic variation for the switchpoint in the mite Rhizoglyphus echinopus, in which males are either fighters or scramblers. The conditionality of male dimorphism varied among inbred lines, indicating that there was genetic variation for switchpoints in the base population, as predicted by the ET model. Our results also suggest a mixture between canalized and conditional strategists in R. echinopus. We propose that major genes that canalize morph expression and affect the extent to which a trait can be conditionally expressed could be a feature of the genetic architecture of threshold traits in other taxa.
多态性特征广泛存在，代表了一种对环境线索敏感的条件策略。环境线索阈值 (ET) 模型将替代表型之间的转换点视为具有正态分布变异的多基因数量性状。然而，转换点的遗传变异很少被经验性地探索。在这里，我们使用近交系来研究螨 Rhizoglyphus echinopus 中转换点的遗传变异，其中雄性要么是斗士要么是混战者。雄性二态性的条件性在近交系之间存在差异，这表明基础种群中存在转换点的遗传变异，这与 ET 模型的预测一致。我们的结果还表明，R. echinopus 中存在 canalized 和 conditional 策略者的混合。我们提出，能够 canalize 形态表达并影响特征条件表达程度的主基因可能是其他分类单元阈值特征遗传结构的一个特征。
